In the field of communications technologies, signals are received and sent by using an antenna. Generally speaking, the antenna has certain coverage, and during antenna installation, the coverage of the antenna itself needs to coincide with a range designed by people, so that the coverage of the antenna itself may be adjusted by adjusting a downtilt angle of the antenna. The so-called downtilt angle of the antenna is also called a pitch angle of the antenna, which is an included angle between the antenna and a horizontal direction.
In usual situation, adjustment of the downtilt angle of the antenna may be implemented through mechanical tilt and electrical tilt. The mechanical tilt is to physically tilt the antenna downwards. However, when the antenna is physically tilted downwards, construction and maintenance are inconvenient, and an adjusting precision of the downtilt angle is relatively low (for example, a step precision is approximately 1°). Therefore, in general situation, the electrical tilt may be adopted, a principle of the electrical tilt is to change amplitude values of a vertical component and a horizontal component by changing a dipole phase of a linear array antenna, so as to change a resultant strength, thereby enabling a vertical directivity pattern of the antenna to be tilted, achieving an objective that the antenna keeps still for adjusting the downtilt angle of the antenna.
When the downtilt angle of the antenna is adjusted by using the electrical tilt manner, the downtilt angle of a wave beam of the antenna may be adjusted by changing a phase of the antenna. For a multi-frequency antenna having at least two antenna units (the multi-frequency antenna may implement functions of at least two frequency bands, for example, one antenna unit implements a function of a 800 MHz frequency band, and the other antenna unit implements a function of a 3 G frequency band), the downtilt angle of each antenna unit may be modulated by individually modulating a phase of a phase adjustment unit corresponding to each antenna unit. Therefore, it is necessary to configure a transmission mechanism for each phase adjustment unit, where each transmission mechanism is connected to a driving apparatus (RCU, Remote Control Unit, remote control unit, also called a driving apparatus) in one-to-one correspondence. As shown in FIG. 1, a tri-frequency antenna is taken as an example for illustration, the tri-frequency antenna has three phase adjustment units 11 corresponding to antenna units 14, a transmission mechanism 12 is disposed for each phase adjustment unit 11, each transmission mechanism 12 is connected to a driving apparatus 13 in one-to-one correspondence, the driving apparatus 13 controls the corresponding transmission mechanism 12 to translate, and a phase of the corresponding phase adjustment unit 11 is modulated through the translation of the transmission mechanism 12, so as to implement modulating downtilt angles of the antenna units 14.
In a procedure of implementing the used process, the inventors find that the prior art at least has the following problems:
Because a driving apparatus is disposed for each corresponding phase adjustment unit, the more frequency bands included in a multi-frequency antenna are, the more the driving apparatuses to be used are, and cost of a single driving apparatus is relatively high, thereby inevitably resulting in rising of cost of the multi-frequency antenna.